Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds real value the annotations don't: the 1-credit cost. It says nothing about caching behavior (cache_max_age), failure modes for private/deleted videos, or rate limits.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences, front-loaded with the resource and then the returned field list plus cost. No filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema, so field enumeration substitutes for it, and cost is disclosed. But for a paid, open-world fetch the description omits what happens on invalid/private URLs, whether missing fields are omitted or null, and what cache_max_age does — meaningful gaps for a 2-param tool with 50% schema coverage.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 50% and description is silent on parameters, but the schema itself documents the critical url format (watch URL or bare permalink id) thoroughly. cache_max_age remains undocumented in both places, which caps this below a 5.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States the verb-less but unambiguous purpose: retrieve public metadata for a single Rumble video, and enumerates the fields returned. It is distinguishable from siblings like rumble_search and rumble_channelVideos, though it never names them explicitly.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

No guidance on when to use this versus rumble_search, rumble_channelVideos, rumble_comments, or rumble_transcript — the natural 'I have a URL, I want X' family. Only the implicit signal is the single-video scope and the url requirement.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.